Artificial hip joints are known in which a femur implant is introduced into a bodily femur, after a head of the bodily joint has been removed. A joint cavity is introduced into the hip as a counter bearing, which, as an abutment, can accommodate a spherical or partially spherical head of the femur implant. Seating the implants precisely is a fundamental criterion for successfully implanting a hip joint. Even the smallest deviations can lead to excessively rapid wear and tear and, therefore, to a short service life of the hip joint implant. In the event of a sudden stress, such as, for example, an impact, a hip implant, which is not introduced precisely, can easily be dislocated or loosened. Therefore, it is advantageous to intra-operatively verify that an implanted joint is correctly seated and positioned.
It is known that, while implanting a hip joint, a surgeon manually moves a patient's leg in various directions until it is prevented from moving further by the patient's anatomy, the implanted components meeting adjacent bones, or encumbrances by tissues or ligaments. An experienced surgeon uses this manual movement to assess the flexibility of the joint and, therefore, how to correctly seat the individual components of an implanted joint. However, a surgeon can only very roughly assess whether flexibility ascertained and assessed in this way is sufficient for the patient's daily life.
A device and a method for determining the position of a component of an implant are known from U.S. Pat. No. 6,002,859, in which a model of the joint and the implant components are generated and a movement of the joint is simulated using the models.